Coupling spaced bond pads to a contact

ABSTRACT

Two dice may be provided within a single package so that one pin and associated leadfinger may be coupled to bond pads on different dice. This may mean that two different bond pads on different dice are coupled, for example by wirebonding, to the same leadfinger. An adhesive tape may be secured so as to bridge the two dice. One or more conductive traces are formed on the upper side of the adhesive tape and adhesive is provided on the other side to secure the tape to the two dice. As a result, wire bonds may be made from a pad on one die to a trace and then from the opposite side of the trace to a leadfinger. At the same time, a wire bond may be made from a pad on the other die to the same leadfinger. In another embodiment, an adhesive tape with a conductive trace on it may be used as a wire bond bridge to join spaced bond pads on a single chip.

BACKGROUND

[0001] This invention relates generally to packaging integrated circuitdevices.

[0002] In some cases it is desirable to provide two integrated circuitdevices inside a single package. Sometimes, it may not be feasible tointegrate the components of both integrated circuits into a singleintegrated circuit. Thus, two integrated circuit devices may be combinedwithin a single package to give combined capabilities at a plurality ofoutput pins.

[0003] At times, signals from pads on the two different dice need to becoupled to the same output pin. One reason why this may occur is thatthe number of pins on the package may be limited. Thus, it may beundesirable to have two separate pins that provide or receive the samesignal.

[0004] The location of bond pads between two dice may not allow directwirebonding from both pads to a common leadfinger. This is especiallylikely to occur when two separate dice are used within the same package.

[0005] Thus, there is a need for a way to allow spaced apart bond padsto be coupled to the same contact.

SUMMARY

[0006] In accordance with one aspect, a method of electrically couplingfirst and second bond pads on different chips to the same contactincludes positioning a conductive trace on a support between thedifferent chips. The first bond pad is coupled to the trace. The traceis coupled to the contact. The second bond pad is then coupled to thecontact.

[0007] Other aspects are set forth in the accompanying detaileddescription and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a greatly enlarged top plan view of one embodiment ofthe present invention;

[0009]FIG. 2 is cross-sectional view taken generally along the line 2-2in FIG. 1;

[0010]FIG. 3 is a greatly enlarged top plan view of another embodimentof the present invention;

[0011]FIG. 4 is a greatly enlarged top plan view of still anotherembodiment of the present invention; and

[0012]FIG. 5 is a greatly enlarged longitudinal cross-sectional view ofanother embodiment of the present invention.

DETAILED DESCRIPTION

[0013] Referring to FIG. 1, an integrated circuit package 10 may containa pair of chips 14 and 16. In one embodiment of the present invention,each chip may be a memory array. It may be desirable to couple some ofthe bond pads 18 and 20 on each chip to the same leadfinger 22 a forconnection to the same external pin 12 a. This may be useful for pinsthat provide output or input signals for the pair of dice.

[0014] Each chip includes bond pads 18 or 20 which may be coupled bywire bond wires 30 to leadfingers 22 and pins 12. A bond pad 18 on thedie 14 may be coupled to a leadfinger 22 a on the die 20 using anadhesive tape 32. The adhesive tape 32, adhesively secured to both dice,bridges the gap A between the two dice. A plurality of parallelconductive traces 24 may be pre-formed on the tape 32. Thus, a pluralityof avenues for interconnection between the two dice are made availableby the parallel conductive traces 24.

[0015] Thus, for example, the bond pad 18 a may be coupled by a wirebond wire 26 to one end of a trace 24. The other end of the trace 24 iscoupled by a wire bond 28 to the leadfinger 22 a. Similarly, the pad 20a is coupled by the wire 30 to the same leadfinger 22 a. In this way,both pads 20 a and 18 a are coupled to the same pin 12 a.

[0016] Referring to FIG. 2, the tape 32 may have a plurality of traces24 deposited thereon on one side of the tape with adhesive on the otherside of the tape. The tape may be adhesively secured to both die 14 and16 with the traces 24 facing upwardly. A die coat may be used toelectrically isolate the tape 32 from the chips 14 and 16. Theconductive trace may be coated with gold, for example using an immersiontechnique, while the adhesive layer on the tape is protected. While aplurality of straight-lined conductive traces are illustrated, othershapes are possible as well, including diagonal or curved shapes.

[0017] The overall package 10 may be encapsulated in a material 34 as isconventional. The pins 12 extend out of the package 10 and are coupledto the dice 14 and 16 through the leadfingers 22 and the wires 28, 30and 26. The leadfingers 22 may be coupled to the dice 14 and 20 usinglead-on-chip (LOC) tape 36 as is conventional.

[0018] Thus, two dice can be contained in the same package and the pincount of the package may be reduced compared to the number of pins thatwould be needed to provide a separate pin for every single pad. Thisresults in economies and compactness and makes it more feasible tocombine multiple dice in a single integrated circuit package.

[0019] The tape 32 may be formed by bonding ductile copper foil to thin,flexible dielectric materials. Suitable dielectric materials includingpolyimide, polyester terephthalate, random fiber aramid, polyamide-imideTeflon®, and polyvinyl chloride. In addition, a non-woven mat of dacronpolyester and glass fibers saturated in B-stage epoxy may be used.Copper foils may be directly clad to B-stage material. Suitableadhesives include epoxies, polyesters or acrylics. Epoxy systems includemodified epoxies known as phenolic butyrals and nitrile phenolics.Acrylic adhesive systems may be used in high temperature applications.Polyesters can be used with polyester film. Metallic coated films mayalso be made using advanced vacuum deposition technology to bond copperto polyimide for example. Specially treated polyimide films may have anultra thin coating of barrier metal applied to promote copper adhesion.The copper may then be electrodeposited onto the film.

[0020] In accordance with another embodiment of the present inventionshown in FIG. 3, a die 40 may be contained in a package 42. A pin 12 mayconnect to a leadfinger 22 proximate to a bond pad 20. In this case, anadhesive tape 32 a extends along the length of the die 40 from aleadfinger 22 on one end to a leadfinger 22 b, on the other end, coupledto a pin 12 b. A connection can be made from a bond pad 20 c, widelyspaced from the leadfinger 22 b, using a conductive trace 24 a formed onthe tape 32 a. For example, the bond pads 20 and 20 c may be spaced toofar apart to couple them by wirebonding.

[0021] Thus, a wire bond is made from the bond pad 20 c to one end ofthe trace 24 a. A wire bond is then made from the other end of the trace24 a to the leadfinger 22 b. A wire bond may also be made from the bondpad 20 b to the leadfinger 22 b. In this way, two different bond pads,which are widely spaced apart, may be connected to the same leadfinger.

[0022] Referring next to FIG. 4, a package 44 includes a pair of bondpads 18 b and 18 c on a chip 14. The bond pads 18 b and 18 c may becoupled to the same leadfinger 22 b on a chip 16 using a tape 32 with anL-shaped trace 24 b. One end of the longer arm of the trace 24 b may bewirebonded to the bond pad 18 b. The other end of the longer arm of thetrace may be wirebonded to the bond pad 18 c. The short arm of theL-shaped trace 24 b may be wirebonded directly to the leadfinger 22 b.Similarly, the bond pad 20 a on the chip 16 may be wirebonded to thetrace 22 b. In this case, three different wire bond bond pads on twodifferent chips may be coupled to the same trace 22 b. Thus, by customdesigning the trace 24 on the tape 32, a variety of interconnectionarrangements are possible.

[0023] Referring now to FIG. 5, still another embodiment of the presentinvention includes an adhesive tape 32 b secured for example to a die16. The embodiment shown in FIG. 5 is applicable to tape secured to onedie as illustrated in FIGS. 3 and tape secured across two dice asillustrated in FIGS. 1, 2 and 4.

[0024] The tape 32 b may be pre-attached to leadfingers 22. The tape 32b includes a tape core 42 covered by a conductive trace 24 c which mayextend along the entire length of the tape 32 a. An insulator 44 may bedisposed along two opposed longitudinally displaced edges. Thus, awindow 43 is defined immediately between the longitudinal end portionswhich may be covered by the insulator 44. The insulator 44 may becovered by an adhesive material 46. The adhesive material 46 may be thesame as the adhesive at the joint 48 formed by the tape 32 b.Conventional adhesives used for lead-on-chip (LOC) tape may be utilizedfor this function.

[0025] Thus, the tape 32 b may be pre-taped to the leadfingers 32. Thetape 32 b may then be applied using the adhesive 48 to the surface ofone or more dice 16. Preferably, the tape runs longitudinally along thelength of the die 16. This enables free access from either side in thelatitudinal direction to bond pads along the die. For reference, in FIG.1, the longitudinal direction would be up and down on the page.

[0026] With the embodiment shown in FIG. 5, the tape 32 b may bepre-attached to an interposer such as a leadframe 22 without concern forshorting to the leadframe 22. Namely, the insulator 46 prevents shortingof the trace 24 c to the leadframe fingers 22. Thus, in some instances,the tape 32 b, shown in FIG. 5, may be more easily applied as acomposite unit including a leadframe with the tape pre-attached.Moreover, the tape may not only provide the interconnection functiondescribed above, but may also function to secure the leadframe to one ormore dice.

[0027] The tape 32 b may be used in the same fashion as the tape 32. Itmay act as a bridge, for example, to allow wire bonds to extend from abond pad to the conductive trace 24 c and from the conductive trace 24 cto a leadfinger.

[0028] While the present invention has been described with respect to alimited number of embodiments, those skilled in the art will appreciatenumerous modifications and variations therefrom. It is intended that theappended claims cover all such modifications and variations as fallwithin the true spirit and scope of this present invention.

What is claimed is:
 1. A method of electrically coupling first andsecond bond pads to the same contact comprising: securing a tape, with aconductive trace, on a support; wirebonding said first bond pad to saidtrace; wirebonding said trace to said contact; and wirebonding saidsecond bond pad to said contact.
 2. The method of claim 1 whereinsecuring a tape includes forming a plurality of conductive traces onadhesive tape.
 3. The method of claim 1 wherein securing a tape includessecuring said tape across two chips, said first bond pad being on one ofsaid chips and said second bond pad being on the other of said chips. 4.The method of claim 1 further including coupling said pair of bond padson different chips to a leadfinger.
 5. The method of claim 1 includingcoupling a first and second bond pad on the same chip.
 6. The method ofclaim 1 including using said tape to secure a leadframe to a die.
 7. Apackaged integrated circuit device comprising: a first chip and a secondchip, one of said chips having a contact; an adhesive tape adhesivelycoupled to said first and second chips, said tape having a trace formedon said tape; a first bond pad on one of said chips and a second bondpad on the other of said chips, said first bond pad being wire bonded tosaid conductive trace, said conductive trace also being wirebonded to acontact; and said second bond pad being wirebonded to said contact. 8.The device of claim 7 including a plurality of conductive traces formedon said tape.
 9. The device of claim 7 wherein said contact is aleadfinger.
 10. The device of claim 7 including a package containingsaid first and second chips.
 11. The device of claim 7 wherein saidtrace is gold coated.
 12. The device of claim 7 including a leadframe,wherein said tape couples said leadframe to said chips and said contactis part of said leadframe.
 13. A method of electrically coupling firstand second bond pads on different dice to a leadfinger comprising:packaging said first and second chips in the same package; providing aleadframe for said chips; positioning an adhesive tape on each of saidchips, said adhesive tape having a conductive trace formed thereon;wirebonding a first bond pad on said first chip to one end of saidconductive trace and wirebonding the other end of said conductive traceto said leadframe; and wirebonding a second bond pad on said second chipto said leadframe.
 14. The method of claim 13 including using said tapeto secure a leadframe to said chips.
 15. The method of claim 14including insulating said chips from said trace.
 16. An integratedcircuit device comprising: an integrated circuit chip having a pair ofspaced apart bond pads and a pin; an adhesive tape having a conductivetrace formed on said tape, said tape arranged along a path between saidspaced apart bond pads; a wire bond from one said bond pads to saidtrace; a wire bond from said trace to said pin; and a wire bond from theother bond pad to said pin.
 17. The device of claim 16 wherein saidtrace is gold coated.
 18. The device of claim 16 wherein said pinincludes a leadfinger.
 19. The device of claim 16 wherein said bond padsare spaced too far apart to allow them to be wirebonded to one another.20. The device of claim 16 including a leadframe, wherein said tapecouples said leadframe to said chip and said contact is part of saidleadframe.
 21. A method of coupling spaced apart bond pads to the samecontact comprising: wirebonding one of said bond pads to a trace formedon an adhesive tape; wirebonding the trace to the contact; andwirebonding the other of said bond pads to said contact.
 22. The methodof claim 21 including securing said tape on a chip.
 23. The method ofclaim 22 including arranging said tape so that said trace extendsbetween said bond pads.
 24. The method of claim 23 including goldcoating said trace.
 25. The method of claim 21 including using said tapeto secure a leadframe to a die.
 26. A method of coupling spaced apartbond pads to the same contact comprising: securing an interposer to adie using adhesive tape; wirebonding a first bond pad to a trace formedon said adhesive tape; wirebonding the trace to the contact; andwirebonding a second bond pad to said contact.
 27. The method of claim26 wherein wirebonding the second bond pad to said contact includeswirebonding the second bond pad to said interposer.
 28. The method ofclaim 26 including securing said tape on a chip.
 29. The method of claim28 including arranging said tape to extend longitudinally on said chip.30. The method of claim 29 including gold coating said trace.
 31. Themethod of claim 26 including adhesively securing said tape to saidinterposer and adhesively securing said tape to a die.
 32. The method ofclaim 31 including insulating said interposer from said trace.
 33. Anadhesive tape for making connections on integrated circuit chipscomprising: a flexible tape layer having adhesive on one side thereof; aconductive trace attached to the other side of said tape; insulatorcovering a portion of said conductive trace; and adhesive secured oversaid insulator.
 34. The tape of claim 33 wherein said tape is adapted tocouple an interposer to a die.
 35. The tape of claim 33 wherein saidinterposer is a leadframe.
 36. The tape of claim 35 wherein saidinsulator is positioned between said leadframe and said trace.
 37. Aninterposer comprising: a structure; an adhesive tape having a lower sideand an upper side, said upper side secured to said structure; aconductive trace defined on said upper side of said adhesive tape; thelower side of said adhesive tape containing adhesive for securing saidtape to a die; an insulator covering a portion of said conductive trace;and an adhesive material on said insulator to connect said tape to saidstructure.
 38. The interposer of claim 37 wherein said structure is aleadframe.
 39. A method comprising: providing an adhesive tape on aleadframe; using said adhesive tape to connect said leadframe to a die;and forming wire bonds from said die to said adhesive tape.
 40. Themethod of claim 39 including forming a conductive trace on said adhesivetape.
 41. The method of claim 40 including insulating said conductivetrace from said leadframe.
 42. The method of claim 41 includingwirebonding from a bond pad to said trace and from said trace to saidleadfinger.
 43. The method of claim 42 including securing said tape to apair of dice.